This library was a backport of the Python 3 "selectors" library. It is
useful to provide a better selector interface for Python2, to address some
issues of the plain old select.select, mentioned in the next patch.
The code [1] was ported using the MIT license, with some minor modifications
to make our test happy:
1. "# no-check-code" was added since it's foreign code.
2. "from __future__ import absolute_import" was added.
3. "from collections import namedtuple, Mapping" changed to avoid direct
symbol import.
[1]: d27dbd2fdc/selectors2.py
# no-check-commit
